Microkorg keys and cutoff not working

breadfoot · Post by **breadfoot** » Wed Jun 09, 2021 1:26 pm

Hi everyone!

I bought a microkorg off ebay a few years back and the cutoff knob never worked. I replaced it with a new pot wwithout any change. I recently dusted it off to have another crack and now the keyboard does not work. I have checked all connections etc, the demo music plays so there is audio, just zero input from keyboard.

I can’t do a factory reset due to the cutoff issue - is there another way to do this via hardware? I’m not afraid to dive inside.

The keys do output a MIDI signal, the cutroff does not.

Any insight or info on how to identify either issue would be appreciated, I know the basics of multimeter use if that is any help.

Thanks

OpAmp · Post by **OpAmp** » Wed Jun 09, 2021 9:12 pm

Hi,

Non working keyboard:
* Is the setting Local maybe off? (Edit Select 2 = MIDI, 2/Reso knob)
* What happens if you send MIDI notes to it using MIDI IN? (Make sure it uses the same channel as the notes of the keyboard on MIDI OUT)

Non working 1/Cutoff:
* You did not mention it, did you check the pot output voltages?
* Google the service manual and have a look at the schematics for the pot. The last point you can check it is at the main cpu. Not sure that you can easily access the pin using a multimeter without risking to create shorts...

Good luck!

breadfoot · Post by **breadfoot** » Wed Jun 16, 2021 1:01 pm

Hey sorry for the slow response.

Things are a bit hectic buit I'll look into this first chance I get.

Thanks!

breadfoot · Post by **breadfoot** » Tue Jan 18, 2022 11:05 am

Hi I hope everyoine is well in these crazy times!

So I’m diving back into this and to give you an update. I’ve set up another midi keyboard to send to the microkorg and even though it is receiving the signal (at least the LED on the MIDI cable connecting it lights up when a key/knob is pressed) no audio is produced. This makes it difficult to check the cutoff (please let me know if I misunderstood what you were asking).

The demo audio works through headphone and line out, and Ableton Live receives the keyboard midi signals from the microkorg, so I’m guessing the keyboard is OK.

I have checked that ext MIDI signals are being received by the keyboard as I can control the MIDI Clock on the microkorg externally via Live. I’m guessing this means the issue is more complicated than I thought. Local MIDI on/off makes no difference.

Voltages on 1/cutoff are 3.285v (constant) for one of the middle pins, and 0-3v on the other middle pin when the pot is adjusted.

Apologies for the non-technical language and any misunderstandings - I don’t have much of a clue what I’m doing here.

Thanks for you help!

Brad

OpAmp · Post by **OpAmp** » Wed Jan 19, 2022 9:27 pm

Hi,

I’ve set up another midi keyboard to send to the microkorg and even though it is receiving the signal (at least the LED on the MIDI cable connecting it lights up when a key/knob is pressed) no audio is produced.

That is what I meant. You also say that you can control the clock. So that looks like that MIDI IN is working. Are you sure you have the same MIDI channel on the external keyboard?

It is a bit weird according to me.
The microKorg keyboard does send out MIDI notes, but they don't sound. An external keyboard seems to send notes, but they don't sound either... Looks like a severe problem...

Voltages on 1/cutoff are 3.285v (constant) for one of the middle pins, and 0-3v on the other middle pin when the pot is adjusted.

That looks ok.

Maybe you can bring the board to someone to have a look at it. Else I'm afraid you need to give up the synth or just use it as a MIDI controller.

Have fun!